Frictional mechanism



Oct. 2, 1945.' v W. H. HUNTER 2,386,115'

. FRIGTIONAL MECHANISM Filed Deo. 11., 1945 2 sheets-sheety 1 85 72 -E M i @j oct. 2, 1945. A -W, H, HUNTER 2,386,116

FRICTIONAL MECHANI SM Filed Dec@ 11, 1945 2 sheets-sheet 2' www!! mmli'n l Patented Oct. 2,4 .1945

UNITED ,sm'rizs4 PATENT i ori-'nce' FRICTIONAL MECHANISM Willson H; Hunter, Lakewood, Ohio, assigner to The B. F. Goodrich Company, New York, N. Y., a corporation of New York Application December 11, 1943, Serial No. 513,822

1s claims. l(criss-152) v This inventionrelates frictional mechanisms for rotatable bodies such as brakes for Wheels of aircraft or other vehicles although features of the invention areuseful in other mechanisms such as clutches operated by uid pressure.

The principal objects of the invention are to provide dependable operation, to provide for facility of maintenance, and to provide for longevity of the mechanism.

Further objects `of the invention are to provide for concealing and protecting the retractor springs and associated parts and to provide for convenient replacement of retractor springs and other brake elements.

These and further objects will become apparent from the following description and accompanying drawings in which Figure 1 is a side elevation of africtional mechanism suitable for a brake, partly broken away and partly in section, constructed in accordance Fig. 7 is' a section taken along the line 1-1 of Fig. 4.

Fig. 8 is a side elevation of a still further modi-l fied construction, partly broken away and partly in section.

tube I5-. For retaining the friction blocks against the expander tube, the` friction blocks I1 have axially disposed slots I9 formed in their inner surfaces near the circumferential ends of the blocks under-cut from the inner peripheral surface 'of the block toward thelend of the block at an angle oblique to a radius of the structure and terminating at 2| short of such end of the block.

That portion of the inner peripheral surface 20 of the,friction blocks that lies between the slots I9 and the end of friction block I1 is re- ,lieved so that a recess 2l connecting with the -slot I9 is formed in each end of each block to accommodate the thickness of a C-shaped clip retractorspring preferably extending the width ofthe channel'll and having its radial margins 26 inwardly bent to engage the slots I5 and i preferably rounded to be received in the under- Fig. 9 is a sectional view taken along the line Q-Q of Fig. 8. y Y

Fig. 10 is a section taken along the line IIt--IIJ of Fig. 8. y

Referring to the embodiment of the invention shown in Figs. 1 and 2, a torque frame I0 is pro--` holes I6 to an associated mounting flange of a shaft (not shown). A series of friction blocks I1 is mounted over the annular expander tube I5 within the channel I4 so that these blocks can move radially into frictional engagement with a rotatable iriction member or brake drum IB when fluid pressure is applied to the expander cut slots I9 of adjacent friction blocks I1 while permitting some relative movement of the blocks. The arrangement is such that, as the friction blocks l1 move radially outward under the fluid pressure of thel expander tube I5, lthe rounded margins 26 of the springs 25 exert counter-pressure on the walls 21 of the undercut slots tending to force the blocks together and to contract the series of blocks to a lesser circumference. When radial pressure is released from the blocks, the counter-pressure exerted on the walls 21 of the undercut slots I9 in the adiacenti block ends returns the blocks to their original position in the channel Il of thetorque frame Ill bydrawing the blocks toward one another, thus reducing their circumference.

,The springs' 25 may be substantially equal in Width to theblocks I1 and completely cover the space between the expander tubeand the gap between adjacent blocks thereby protecting the tube from pinching and from heat radiating vfrom the brake drum.

The end faces 32,' 32 of each pair of adjacent blocks are adapted to bear on a thrust pin 28, which may be of square cross section,to limit undesirable circumferential..displacementl of the blocks I1 as the blocks I1 are moved. in radial compression against a friction drum I8. Such pins 28 may be arranged between each successive pair of friction blocks, thereby 'dividing the torsional load. The pins are arranged to engage flanges II and I2 and are secured in a removable manner for facility of assembly and repair. For this purpose, the head 29 of the thrust pin 28, which passes through the flange I2, seats against the torque flange I2"-and if desired the pin 28 may be tack welded tothe torque flange I2 at the head 2Q. The other end 3 of the thrust pin 28 extends outward through the flange il and preferably has a reduced neck 28a which its into the narrow part 34 of a button hole slot 35 of a locking ring 3'? seated on -the outer face of iiange li. The outmost end 3G of the thrust pins 2d is no largerv than the body of the pin 2li so that it may be inserted through the space between the friction blocks l'i during assembly and through the hole 32 of the locking ring di. The ring tl may thenbe shifted to move the narrow neck 3d of the vbutton hole slot 35 about the reduced portion 28a of the pin 26 and locked against further rotation by a locking screw dll engaging the :flange ii so that the ring 3l cannot change position and free the thrust pins 2E.

with the thrust pms 2e rocked on the torque frame it, the friction yblocks ll may be moved radially between the pins 2t into radial compression against the drum i8 by the pressure exerted by the expander tube l5 to retard or 'stop the rotatable drum i8 while, the circumferential thrust on-the blocks .is transferred to the ang'es il; i2 by the pins 28. When' the pressure is released rom the frictionblocks il, the retractor springs 25, which exert pressure on the walls 2l of the undercut slots i9, can urge the blocks closer together and move these blocks radially inward and'away from the frictional drum lli.

In assembling the structure, with the iiange ll removed, the expander tube i5 may be laid in the vchannel ld and the friction blocks and springs 25 assembled thereabout. The pins 2u are passed between the blocks and inserted in the ange ll when the'latter is placed in position. A single movement ofthe locking ring 3i locks all 'of the pins simultaneously and the screw Se locks the I ring in place.

The expander tube i5 preferably has a working face ma and a thinner back wall @i dening an inflation chamber l2 having outwardly extendingl margins d3. The chamber l2 may be substantially closed in the deflated-condition; If desired, the expander tube may have recesses, such as the grooves lil formed in its working face, as such recesses have been found in many cases to eliminate orreduce objectionable noise and vibration in braking.

In some assemblies it may be desirableA to dis'- pense with the locking ring described in the embodiment above described and to use a thrust pin 58 of the design as shown in the .embodiment of Fig. 3 in which one end 5D of the pin 56 is tapered, as at 5'@ to t tightly in a tapered hole El 'in the torque ange 52 and an opposite end 53 ts in an'opening 5d through tor-gue flange 55. A head 5B of the thrust pin '5S may be tack welded as at 5S to fasten the pin in position in the torque frame of which anges 52, 5 are held together by bolts 6b.. f

Referring to the embodiment of the invention shown in Figs. d to '1, a torque frame le comprises opposite ilanges il and l2 fastened together by bolts 'i3 and adapted to be mounted on a flange of a shaft (not shown) by means of holes 1d. The iangesfil and l2 form a circumferential channel adapted to seat an annular` expander tube 16 at the bottom of the channel. Seated upon the expander tube within the channel is a series of `pressure blocks il of suitable still material. To provide a high coemcient of friction at the outer fac as of the pressure blocks, and also to provide for reduction of weight, and to insulate the tube against heat, these are preferably made of molded vplastic material Such as Vassegno Bakelite, hard rubber. or the like. The adjacent blocks il are separated by thrust pins i8 extending between the blocks through openings 'i9 in the torque ange il, and the opposite end Sli 5 of each pin is tapered and ntted into a tapered hole BI in the torque flange l2.

After assembly of the parts, the thrust pin is tack welded as atA $2' or otherwise attached to securely fasten the pin to the torque ange ll.

l0 The end faces 83 of adjacent pressure blocks c'ooperate with the thrust pins 'ill to prevent circumferential slippage of the blocks when the blocks move radially under pressure delivered to the blocks 11 by the annular expander tube le.

i5 For retraeting the blocks when pressure of the expander tube is released, a shallow hole 35 is formed in the lateral faces of the pressure blocks located-near but away from the axial end faces 83 thereof and the side faces of the blocks are 205 recessed as at el from the holes 85 V'te the adjal cent end facesv oi.' the blocks and below the outer '\cicumference face, -to receive a c-shaped clip g spring 88. This recess 8l provides a space to 'accommodate the thickness of the spring so that the same will not have objectionable interference with the inner vfaces of the torque angesduring radial movement of fthe pressure blocks.

The spring 88, illustrated for example in Fig. 'l

of the drawings, may be of wire and has inturned 3o ends 89 adapted. to enter the/holes t5 of adjacent blocks. The spring ,88 extends under and may bear on the under surace of the thrust pin i8 or operating clearance may be provided between 'the spring and pin.' The ends es of the spring are received in the holes 5 in the adjacent pressure blocks 11 and bear against the sides under tension and thus maintain tension be tween the blocks when the expander tube 'i6 forces thel pressure blocks radially outward so 40 that the tensionthus applied will return the pressure blocks totheir original position by urging the pressure blocks radially inward to a smaller diameter when the fluid pressure is released from the expander tube 1S. Where desired, the springs may bear against the thrust pins, against which they may fulcrum, thereby 'increasing their tensionand providing a condi- 'tion 'of increased tension acting to retract the blocks. Y

A full circle friction band 92 marginally rabbeted at its outer periphery 93, as shown in Fig. 5, is disposed in the channel 15 and in circumferential contact and oating engagement, with the outer peripheral surface of the pressure blocks 11. The radial displacement of the band 92 may be limited by inwardly'turned lips Q5, 96a of the torque flanges i! and i2, engaging over rabbeted margins 32a, 92h of the band S2. The band 92 is resiliently fastened together at e0 its ends @t by a G-shaped clip spring Qwhose construction is illustrated for example in Fig. '6 of the drawings. The lateral edge of the band S2 has shallow holes Si adapted to receive the ends of the springs G8. The holes Si are located 35 at the adjoining ends 95 of the band but are located away froml the adjacent faces t9 thereof. The side faces that lie between the holes Ii and the adjacent end faces 99 of the adjoining ends f the band 92 are recessed at 98 to receive the spuug' 96 'inward of the lateral edge of lthe bans The springs 98 may be of spring wire and have ends Hill inwardlylbenh and terminating in smooth curve IB IA at the end'of thevsprlng. ".I'hes.d inwardly bent curved ends ISU of the spring 86 join the ends of the band byinsernon of the ends of the spring into the holes 91 at each end of 'the band. The smooth curved ends |0| of the spring bear on the walls of the holes 91 and urge the band radially inward to a smaller diameter over the pressure blocks 11.

This construction of the band and adjoining spring provides for circumferential elongation of lthe band 92 when the pressure blocks 11 m'ove in radial compression against the band 92 and thus move the band 92 into frictional engagement with a cooperating drum |03 to retard or completely stop the motion of the latter. By providing the pants of materials such that the coefiicient of friction is greater between the adjacent surfaces of the pressure blocks 1l and .the band 92 than the coeiiicient of friction between the band 92 and the drum |03, for example by providing the blocks 11 of Bakelite or hard rubber acting against the inner face of the band 92 of braking 1. In a frictional mechanism a plurality of circumferentially disposed pressure elements having recesses in their walls and c -shaped springs having converging portions engaging in the recesses of'adjacent elements'in a manner to exert resilient pressure against said elements directly in the circumferential direction for resisting circumferential separating movement of said` ele. ments, said springs being disposed entirely within said recesses of adjacent pressure elements.

2. In a frictional mechanism a pressure band structure having adjacent ends and recesses in the walls of the structure near said ends, and a composition, the latter acting against the metal brake drum, slippage of the band 92 upon the blocks can be prevented or minimized so. that 'the torque will be transmitted to the pressure blocks.

Referring to 'the embodiment of the invention in Figs. 8 to 10 a torque frame I|0 comprises ilanges |02 and |02a fastened together by bolts |03a. The frame is adapted to be mounted on a ange of a shaft (not shown) by means engaging through holes |04. The anges |02 and |02a form an outwardly directed circumferential channel |05 adapted to seat an annular expander tube |06 at the innerv face of the channel. Seated on the expander tube is a' series of pressure .blocks |01 preferably of Bakelite or other suitable plastic material providing light weight and heat insulation A hole |00 is formed in each end, of 'the lateral faces of the pressure blocks located near but away from the axial end faces thereof and the side faces of the pressure blocks are recessed at to receive c-shaped clip springs |20 to retract the blocks. This recess provides a space to accommodate the'thickness of the spring between the torque flanges and the blocks.

The spring |20 illustrated for example in Fig.

10 of the drawings has intumed ends 2 adapted V cumfererrtially toward each other so tlat the* tension thus applied will return the pressure blocks to their original position byurging the pressure blocks radially `inward to a smallerv diameter when the fluid pressure is released from the expander tube |06. The thrust lugs Il! prevent objectionable circumferential displacement of the 4pressure blocks |01 when the frictional system is in operation.

A series of friction blocksli preferably of c-shaped spring having converging portions en'- gaging in said recesses and bridging said ends in a manner directly to resist separating move-- ment 'of said ends, the recesses being of a form to accommodate said spring substantially within the longitudinally extending walls-ofthe band structure, and said springs being disposed entirely within said recesses of said adjacent ends.

3.` A frictional mechanism comprising a pair of concentrically arranged relatively rotatable members, one of said members having a channel open toward the other memberf an expander seated in said channeLa series of pressure elements' upon said expander and movableradially of the channel, spring means' having hooked ends with the hooks facing each other and engaging the 'ends of adjacent elements for resiliently urging them directly in a circumferential direction toward each other, and means for limiting circumferential movement of said elements. l

4. A frictional mechanism comprising a pair of concentrically arranged relatively rotatable mem-p bers, one of said members having flanges defining a channel open toward the other member,`an expander seated in said channel, a series 0f pressure elements upon said expander and movable .radially of the channelled member, spring means f having converging portions seated in lateral margins of the elements and engaging adjacent elements for resiliently urging them directly in a circumferential direction toward each other, and

means for limiting circumferential movement of said elements.

5. A frictional mechanism comprising a pairof concentrically arranged relatively rotatable members, Aone of said members having flanges delining a channel open toward the other member, an

expander seated in said channel, a series of pres `sure elements upon said expander and movable radially of thel channelled member, spring means having converging portions engaging the ends of u adjacent elements for resiliently urging them directly in a circumferential direction toward each other,I and thrust pins extendingvbetween said molded heat-resisting material is disposed in.

ship-lap relation over the pressure blocks I 01 and lap spacesbetween the pressure blocks and thus iianges and between ends of adjacent elements for limiting circumferential movement of said elements. I

6. A frictional mechanism comprising apair of 4concentrically arranged relatively rotatable members, one of said members having separable flanges defining a channel open toward the other member, an expander seated in said channel, a

series of pressure elements upon said expander and movable radially of the channelled member, spring means engaging the ends ofadjacent elements for resiliently urging them toward each flanges defining e. channel open toward the other member, an expander tube seated in said channel, a series of pressure elements upon said expander tube and movable radially of the .channelled member, spring means engaging the ends of adjacent elements for resiliently urging them tsward each other, thrust pins fixed to one of said l flanges extending through openings in the other flange and between ends of adjacent elements for limiting circumferential movement of. said elements, and locking means egaging the ends of the thrust pins at said other ange, said locking means comprising a rotatable ring seated on said other angefand having keyhole openings for admitting the ends of the thrust pins and said pins having reduced necks for .engaging in the reduced Portions of said openings.

8. 'A frictional mechanism comprising a pair of concentricallyhrranged relatively rotatable memassente 13. A frictional mechanism comprising apair ci' concentrically arranged relatively rotatable members, one of said members having a channel open toward the other member, an expander tube seated in said channel, aseries of pressure blocks upon said expander tube and movable radially of the channel, spring means engagingthe ends of bers, one of said members having a channel openy toward the other member, expander means vin said channel, a series of pressure elements upon said expander means and movable radially of the channel, said elements having recesses near their ends, and C-shaped springs spanning the space Y between successive blocks and having converging portions engaging in said recesses for retracting the elements.

'9, A frictional mechanism comprising a pair of concentrically arranged relatively Vrotatable members, one of said members having a channel open toward the other member, an expander tube seated in said channel, a series of pressure elements upon said expander tube and movable radially of the channel, thrust elements on one of said flanges and extending between successive pressure elements for limiting circumferentialv movement thereof, said pressureelements having morticesmear'their axial faces, and G-shaped springs spanningtthe-space between successive pressure elements and engaging in the mortices thereof for retracting the pressure elements, said 4spring being engageable with the'under side of said thrust elements to stien the springing action.

seated in said channel, a series of pressure blocks upon said expander and movable radially of the channel, spring means engaging the endsof ad- .jacent pressure blocks for resiliently urging them toward each other, means on said channel and lextending between successive blocks for limiting circumferential movement of said blocks,

and a structure of friction material overlying said pressure. blocks for frictionally engaging the otherrotatable membergi 11. A frictional-mechanism as dened claim 10:11h which said friction structure comprisesa friction. band upon` said pressure blocks.

12, 'A frictional mechanism as defined in claim 10 in which said friction structure comprises a series of friction elements mounted on said pressure blocks in ship-lap arrangement.

adjacent pressure blocks for resillently urging them toward each other, means on said channel and extending between successive blocks for limiting circumferential movement of said blocks, a band of friction material overlying said pressure blocks for frictionally engaging the other rotatable member, the band presenting adjacent ends, and spring means engaging the adjacent nds of said band and resisting circumferential sepa.-

rating movement of said ends.

14. A frictional mechanism comprising a torque frame having a series of openings, an annular expander tube disposed in said frame, pressure elements having openings, C-shaped springs having hooked portions facing each other and. received in the openings of said elements, and a series of torque pins disposed betweensaid elements and received in said openings of said torque frame.

15. A frictional mechanism comprising a pair of concentric friction structures, one of said pair being rotatably mounted in respect to the other of said pair, means to move the radially inner one of said pair into frictional lengagement with lthe other, means to limit circumferential dised to engage and disengage with said friction` drum, an expander tube in said channel to effeet such engagement and disengagement, said' friction elements in said channel havingslots in their inner peripheral surfaces and extending angularly toward the end faces thereof, retractor springs in said slots each generally in its intermediate flat portion and having turned margins received in said slots, a series of thrust pins disposed between adjacent ends of said friction elements, saidthrust pins extending through said flanges to prevent circumferential. displacement of said elements in said channel, and a ring having a series of bayonet locking slots receiving ends of said thrust pins. that extend through said flanges to lock said thrust pins inposition.

17. A frictional mechanism comprising a torque frame, annular anges extending from said torque frame, a frictional drum rotatably mounted in relation to said torque frame, an'expander tube disposed between said torque flanges, a series of pressure blocks disposed on said tube and having recesses in their sides, thrust resistingV means disposed between adjacent pairs of blocks, a series -of retractor Springs' having bent margins disposed in said recesses of adjacent pres- 'sure blocks and adapted to exert pressure on the blocks to `resist circumferential separating movement thereof, a friction band' disposed on said pressure blocks, said band having a pair of end tions, and springs having bent margins in said openings for resisting separating movementl of said end portions.

18. A friction'al mechanism comprising a torque frame, annular nanges extending from said torque trame, a frictioai drum rotatably mounted in relation to said torque traine, an ex pander tube disposed between' said torque iianges,

' a. series ot pressure blocks having recesses in 10 I a,sse,11o 5 portions and openings in the sides of said porl their sides near end portions of the blocks, said recesses extending to the adjoining ends of the blocks, torque means between blocks. retractor vsprings each having bent end portions in said 'receases and substantially within the lateral connnes of the blocks, and friction elements. disposed on said pressure blocks and fastened in circumferentially overlapping relation to said blocks to break joints with said blocks.

' WILLSON H. HUNTER. 

